The worldwide spread of the Internet is increasing the amount of the data traffic in optical communication networks year by year. To address such increase, there is a need for higher performances, such as further speed up, further reduction in power consumption and the like, in the semiconductor light sources and modulators that are key devices in optical fiber communication networks or the integrated light sources integrating the same. Until now, edge emitting lasers using a cleave of a compound semiconductor as a facet have predominated. However, in recent years, the research and development of vertical cavity surface emitting lasers that emit light vertically to a surface of a wafer are actively conducted. FIG. 3 shows a cross-sectional structural view of a vertical cavity surface emitting laser lasing in a general wavelength of 850 nm band. In FIG. 3, n-type DBR (Distributed Bragg Reflector) layer(s) 302 are laminated on a GaAs substrate 301. The DBR layers 302 need a high reflectivity of 99 to 99.9% for the purpose of laser oscillation, and is composed of 35 pairs of reflective film layer pairs of n-type Al0.9Ga0.1As layers 302a and n-type Al0.15Ga0.85As layers 302b wherein the reflective film layer pair has different refractive indexes.
The refractive index difference in these layers is approximately 0.4. Moreover, the film thickness d of the respective DBR layers 302a and 303b is given by d=λ/4nr, wherein nr is the refractive index of the semiconductor and λ is the oscillation wavelength. On the n-type DBR layers 302, an n-type Al0.3Ga0.7As-spacer layer 303, a GaAs/Al0.3Ga0.7As MQW active layer 304, and a p-type Al0.3Ga0.7As-spacer layer 305 are continuously laminated, and a p-type DBR layer 307 is furthermore laminated. The p-type DBR layer is composed of 30 pairs of reflective film layer pairs wherein the reflective film layer pair is composed of a p-type Al0.9Ga0.1As layer 307a and a p-type Al0.15Ga0.85As layer 307b. A partial region layer of the p-type Al0.9Ga0.1As layer 307a of the lowest layer in the p-type DBR layer 307 is replaced with a p-type Al0.98Ga0.02As layer, the outer periphery of which is oxidized to form an AlOx-oxidation layer 306. On the p-type DBR layer 307 is formed a p+-type GaAs layer, and a light emission aperture portion is removed. Reference numeral 309 represents a SiO2 passivation layer, reference numeral 310 represents an electrode for p-type semiconductor, and reference numeral 311 represents an electrode for n-type semiconductor provided on the back surface of the substrate. In such wavelength of 850 nm band, the vertical cavity surface emitting lasers has been already put in practical use.